This invention relates to an automatic ice making machine, more particularly to an automatic ice making machine equipped with a protection unit which can effectively prevent compressor burning and waste of power during ice making operation.
Various types of automatic ice making machines for continually making various shapes of ice cakes including cube and plate in large quantities are utilized suitably depending on the applications. For example, popular ice making machines include:
(1) so-called closed cell system ice making machines having a multiplicity of freezing cells opening downward formed in a freezing chamber, in which the freezing cells can separably be closed with a water tray, and a water for freezing is injected into the freezing cells through the water tray to form ice cubes gradually therein;
(2) so-called open cell system ice making machines having a multiplicity of freezing cells opening downward, in which a water to be frozen is directly injected into the freezing cells in the absence of the water tray to form ice cubes in the freezing cells; and
(3) flow-down system ice making machines having a tilted freezing plate, in which a water to be frozen is supplied to flow on the upper or lower surface of the freezing plate to form an ice plate on the corresponding surface.
These automatic ice making machines generally have an ice making mechanism in the upper part of the machine body and a freezing system for cooling said ice making mechanism at the lower part thereof, said freezing system comprising a compressor, a condenser, a capillary tube, an evaporator, etc.
The evaporator connected to this freezing system is disposed at the ice making section in the ice making mechanism to cool the ice making section; whereas a water to be frozen is circulably fed to the ice making section being cooled to form ice cakes, and upon detection of the growth of the ice cakes to a predetermined size by an ice formation detector which detects completion of ice formation, feeding of the water to be frozen is stopped. Subsequently, by the selective operation of a valve, a heated gaseous cooling medium from the compressor is adapted to be fed through a bypass tube to the evaporator to heat the ice making section and allow the ice cakes formed therein to drop by their own weight, whereby the ice cakes thus released are collected and accumulated in a stocker disposed below the ice making section. Incidentally, a fin and tube type condenser is generally used as the condenser of the freezing system which is forced to be cooled by a cooling fan.
As the protection unit for the freezing system which is actuated during the ice making operation, generally used are a motor protector attached to the compressor (overload protector), a pressure switch which detects the pressure of the cooling medium, etc. Also used are units in which the temperature of the cooling medium being condensed is detected by a temperature element such as thermostat and thermistor to actuate an alarm unit.